What is included in the initial management of methemoglobinemia?

Updated: Dec 09, 2018
  • Author: Mary Denshaw-Burke, MD, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Early clinical recognition of methemoglobinemia is paramount, as patients often have only vague, nonspecific complaints, especially in the initial phase. High levels of methemoglobinemia can be life-threatening and necessitate emergency therapy. Patients with chronic mild increases in methemoglobin level may be completely asymptomatic and require no specific therapy (provided that they have no evidence of end-organ damage).

Once the diagnosis of methemoglobinemia has been confirmed and appropriate management has been initiated, the underlying etiology should be sought. In acquired methemoglobinemia, if the toxin or drug is not known from the history, it may be identified by obtaining blood levels, performing gastric lavage, or both. In asymptomatic patients with low levels of methemoglobin, monitoring serial serum levels may be all that is necessary. The levels normalize over time unless recurrent or chronic exposure to the offending agent occurs.

Treatment is advisable for patients with acute exposure to an oxidizing agent who have methemoglobin levels of 20% or higher. Patients with significant comorbidities (eg, coronary artery disease [CAD] or anemia) may require therapeutic intervention at lower methemoglobin levels (eg, 10%), especially if end-organ dysfunction (eg, cardiac ischemia) is present.

If methemoglobinemia is the result of toxin exposure, then removal of this toxin is imperative. Further ingestion or administration of the drug or chemical should be avoided. If the substance is still present on the skin or clothing, the clothing should be removed and the skin washed thoroughly. These patients may be unstable and should be cared for in a closely monitored situation, with oxygen supplementation provided as needed.

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